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Preparation of metallo porpyrins and photoinducued electron transfer from porphyrins to biointerface

金属卟啉的制备以及从卟啉到生物界面的光诱导电子转移

基本信息

批准号：
14050035
负责人：
OKURA Ichiro
金额：
$ 23.68万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2006
项目状态：
已结题

项目摘要

Photoinduced electron transfer systems, which changes light energy to high-energy electrons, are model systems of natural photosynthesis to harvest solar energy. Electron acceptor linked photosensitizers are one of good system to generate long lifetime charge separated species by light illumination. The charge separated species, however, are achieved in not water solution but organic solvent. There is intense interest in experiments which reveal how achieve charge separated species in aqueous solution. We report that long lifetime charge separated specie in water is generated and that photoinduced hydrogen evolution occurs effectively.Hydrophobic porphyrin-butylviologen-aminopropylviologen triad molecules undergo a photoinduced two-step electron transfer reaction which results in the generation of reduced viologen with a lifetime on the microsecond time scale in aqueous solution. Structure of the viologen linked porphyrin is shown in Fig. 1. The viologen linked porphyrin has a gradually hydrophilic molecule from hydrophobic porphyrin to aminopropylviologen, and facilitates a directional electron transfer to the aminopropylviologen in water, because the two viologen moieties stay under a linear arrangement which shows no intramolecular interaction with face to face of pi-electron between viologens and between the porphyrin ring and viologen. The gradually hydrophilic form also facilitates solvent cages for electron transfer from the phoexcited porphyrin to adjacent viologen, so that electron transfer via the photoexcited singlet state occurs in aqueous solution. The porphyrin was also applied for photoinduced hydrogen evolution system, and effective hydrogen evolution was observed.

光诱导电子转移系统将光能转化为高能电子，是自然光合作用的模型系统，以收获太阳能。电子受体连接型光敏剂是一种利用光照产生长寿命电荷分离物种的良好体系。然而，电荷分离的物种不是在水溶液中而是在有机溶剂中实现的。人们对揭示如何在水溶液中实现电荷分离物种的实验产生了浓厚的兴趣。我们报道了在水溶液中产生长寿命的电荷分离物种和有效的光诱导析氢，疏水性卟啉-丁基紫精-氨丙基紫精三联体分子在水溶液中经历光诱导两步电子转移反应，导致产生寿命在微秒时间尺度上的还原紫精。紫精连接的卟啉的结构如图1所示。紫精连接的卟啉具有从疏水性卟啉到氨丙基紫精的逐渐亲水的分子，并且促进了在水中向氨丙基紫精的定向电子转移，因为两个紫精部分保持线性排列，这显示紫精之间以及卟啉环与紫精之间没有π电子面对面的分子内相互作用。逐渐亲水的形式也有利于溶剂笼的电子转移从光激发卟啉相邻的紫精，使电子转移通过光激发单重态发生在水溶液中。将卟啉应用于光生放氢体系，观察到了有效的放氢。